Search Documents

By Chris Twigge-Molecey

"Over the last 50 years there has been a dramatic evolution in the metallurgical engineering field in Canada. In the 60s the field was dominated by large American and UK groups, often selling major process and equipment packages. The local content was limited to wrap around facilities and the civil and structural work. The mining and metallurgical companies had strong internal teams to lead these projects. Over the decades and business down cycles the large foreign contractors disappeared or re-structured and the mining companies largely shed their engineering and project management groups. The resulting gap was filled by a cadre of local specialist engineering companies, some of whom have grown to be world leaders in the field. The paper traces this evolution and examines the underlying causes and consequences."

Jan 1, 2015

By Ronnie X. Gu, Xing Zheng, Gem-Yeu Ma

Due to implementation of the rotator construction method from which a smooth shaft was anticipated, a full-scale pile load test (Osterberg Method) was performed at Pier 14 Pile 9 of the main span of the New Benicia-Martinez Bridge to confirm the design parameters of the rock sockets. Two levels of load cells were fabricated in the reinforced cage of the rock socket. Each level consisted of three 670-mm Osterberg load cells with a total testing capacity of more than 50 MN in both directions. In an attempt to separate side friction and end beari ng, a 75 mm thick compressible Styrofoam material was placed at the bottom of the cage. The pile load test was carried out in four stages. The multi-level multi stage pile load test data was interpreted for casing friction, side friction for two rock strata, end bearing, and residual side shear values under repeated loading in opposite directions. The side friction from the casing in soils at Stage 2 is approximately 9 MN. The end bearing at the tip of the rock socket at Stage 3 was calculated to be approximately 17 MN at a displacement of about 75 mm. The residual side shear resistance for the 10 m 50% RQD rock strata was calculated to be 9 MN or approximately 50% of initial values, after being pushed 0.3 mm upward in Stage 1, 71 mm downward in Stage 2, then 55.5 mm upward again in Stage 3, and finally 105.3 mm downward in Stage 4. The test results surprising ly indicate that the side shear resistances from both low RQD intensely weathered rock and higher RQD slightly weathered competent rock are about the same at approximately 19 MN. This pile load test provides very critical information for confirming deep shaft design and analyses.

Jan 1, 2005

By A B. Christie

Space-based synthetic aperture radar (SAR) data is becoming available over much of the world, includingNew Zealand. Radar imagery has a number of very advantageous features, including all-weather capability; it also has artifacts, such as layover, which require processing before these data may be used to best effect.   This paper gives an outline of SAR, details the image processing required, and discusses the use of the first New Zealand Japan Earth Resources-1 SAR data to aid geological mapping on the Coromandel Peninsula.

Jan 1, 1994

By Madan M. Singh

Section 516 of Public Law (PL) 95-87, commonly known as the Surface Mining Control and Reclamation Act of 1977 (SMCRA), requires that underground coal mine operators must "adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mine stability, and maintain the value and reasonable foreseeable use of such surface lands, except in those instances where the mining technology used requires planned subsidence in a predictable and controlled manner..." Implied in the constraints of Section 516(b)(1) of SMCRA is a determination of what constitutes "material damage" to surface structures, renewable resource lands, and the capacity for sequential land use following underground mining. The authors have already briefly addressed the subject of damage criteria in relation to surface structures (Bhattacharya et al, 1984). In this paper, an attempt is made to provide quantitative guidelines to ascertain material damage to renewable resource lands, although the data available to establish these criteria are considerably more limited than is the case for surface structures. Besides, many more variables influence the severity of the impact at a given site, making the task of assigning stringent ground movement limits even more complex. This often necessitated use of professional judgement and occasional reverting to a qualitative approach. Hence the reader is cautioned at the very outset that the quantitative limits presented herein are approximate and are primarily intended to serve as rough guides for ascertaining the extent of damage to the renewable resource lands under consideration, and that depending on site-specific conditions the actual damage incurred may differ significantly from that predicted by the proposed criteria. The authors, however, feel that the criteria suggested are somewhat conservative, but realistic. The actual damage observed should generally be less severe than predicted by these criteria. It may also be clarified here that the term "subsidence", as used in this paper, implies the total phenomenon of surface and subsurface effects associated with the mining of minerals and not only the vertical displacement of the surface as is sometimes inferred in the literature.

Jan 1, 1984

By William J. Miles

The markets and applications of Wyoming bentonite deposits are primarily determined by the functional properties of a bentonite ore which results from the unique mineralogy and chemistry of each deposit. Commercial bentonite products contain sodium montmorillonite as the major mineral component, with minor concentrations of accessory minerals such as quartz, opal (silica hydrate), mica, feldspar, gypsum and zeolites. The chemical composition of the sodium montmorillonite influences the functional properties of the bentonite in significant ways. The type and concentration of various accessory minerals also influence the acceptability of the bentonite in each market.

Jan 1, 1995

By Ruixuan Zhang, Yan Li, Shusen Cheng

The high temperature distribution of the blast furnace raceway plays an important role in continuous and steady production. There are a number of techniques which have been developed for flame temperature measurements, but most of them have considerable errors and instability. To obtain more accurate results, an efficient optimization algorithm is necessary. This paper presents a novel measurement approach based on the two-color method and an optimization algorithm using images of raceway flame captured by the RGB CCD (Charged-couple Device) camera to calculate the projection temperature distri- bution. Furthermore, both the back-propagation neural network and the principal component analysis are applied to calibrate the correlation between blackbody temperature and the gray-level intensity. Experimental results obtained from the blast furnace raceway demonstrate that the proposed optimization approach performs well in the measurement offlame temperature compared with the measured temperature.

Mar 1, 2017

By N. Madani, S. Abulkhair

In multivariate geostatistics, it is common to have different types of complexities between variables of interest. In this context, an inequality constraint is an example of complex bivariate relationships. Unfortunately, traditional co-kriging and co-simulation algorithms cannot reproduce this type of bivariate complexity, leading to the overestimation of disturbing elements. This paper proposes a new algorithm based on a hierarchical sequential Gaussian co-simulation framework, integrated with inverse transform sampling, to model inequality constraints between variables. First, the proposed methodology's validity was evaluated by applying it to a real case study from an iron deposit, with an inequality constraint between iron and aluminum oxide. Then the simulated results were compared with a conventional hierarchical co-simulation algorithm to investigate the effect of inverse transform sampling on the quality of the co-simulation. The results showed that the proposed algorithm can reproduce an inequality constraint between variables.

Sep 1, 2021

By S. Kevin McNeil, William Joa, Catherine Johnson, S. Omar Garcia

The geometry of an explosive is known to have a fundamental effect on the resulting shock wave propagation. Typically researchers use a spherical or hemispherical geometry in order to simplify the shock wave so that resultant overpressure and impulse are uniform in all directions. The goal of this research is to understand the overpressure characteristics from a sheet explosive, a geometry often utilized for breeching in the military. In training alone, soldiers can be exposed to several tests per day, which may be contributing to the prevalence of blast induced mild traumatic brain injuries. Using PCB pressure transducers and high speed video, it was found that as the angle departed from normal (perpendicular) to the face of the sheet explosive, the over pressure decreased significantly. When in line with the plane, a decrease of over pressure by as much as 20% was observed. Time of arrival was roughly 20% faster directly in front of the charge with a pressure amplification of 46% relative to a spherical baseline charge of the same mass. This testing may reveal a more complete relationship between the pressure and angle from the explosive that could have applications for military and law enforcement with respect to best practices on blaster location for reduced over pressure exposure.

Jan 1, 2019

By Thomas Leonard Watson

SULPHIDE ore-bodies of more or less lenticular shape occurring in metamorphic crystalline schists, gneisses, and. slates, and conforming closely in strike and usually in dip to the inclosing rock, have been recognized and described along the, Atlantic seaboard from Quebec to Alabama. The ore-bodies do not entirely conform, in all cases, to the structure of the inclosing schists, but they sometimes cut across the foliation in dip, though conforming more closely with the direction of strike. In composition the principal sulphide mineral is usually pyrite or pyrrhotite; or both, accompanied by copper, frequently gold, and almost always some sphalerite and galenite. Other. metallic ores are, so far as these sulphide bodies have been investigated, less common; silver is not uncommon, and in some of the pyrrhotite masses nickel is present in quantity sufficient to be commercially valuable. Cobalt frequently accompanies .the nickel, usually in smaller amount, and the two vary much in relative proportion. Quartz and calcite are probably the most common of the, non-metallic minerals. A number of silicate minerals are frequent representatives in one place or another; garnet, amphibole, biotite, pyroxene, zoisite and others. The sulphide bodies of Virginia, comprising both pyrite and pyrrhotite, are among the most extensive along the Atlantic seaboard. Among the pyrite bodies may be mentioned the well-known and extensively worked mines of Louisa and Prince William, counties, located on' the main pyrite belt (A, Fig. 1) of the middle and northern, eastern Piedmont region in Virginia, and among the pyrrhotite bodies is the famous " Great Gossan Lead "(B, Fig. 1) of the Floyd-Carroll-Graysou coun-

Sep 1, 1907

By James R. Boyle

The Bureau of Mines initiated a program to address short-and long-term objectives of wetlands restoration as a option for reclamation of lands mined for phosphate. The short-term objectives were to identify a suitable wetland test site, initiate an extensive premining monitoring plan, develop an acceptable mining plan, and recontour and revegetate the test site. These goals were accomplished using a unique combination of expertise provided by Federal and State agencies and private industry. A 6.5-ha forested wetland with an associated streambed was offered by private industry as the test site. A premining monitoring program was established and carried out from May 1982 to October 1983. A control site was established to determine ecological changes unrelated to mining. Clearing and mining began in October 1983 and was completed in April 1984. Grading and streambed restoration was completed in February 1986. Revegetation of the site was completed in February 1987. The program to meet the long-term objective of postmining monitoring is described.

Jan 1, 1988

By K. Bullock, M. Levesque, G. Lyle, D. L. Millar

ABSTRACT The options for reducing the carbon footprint of energy use in mining fall into three categories of activity: i) reducing demand, ii) improving energy utilization, and iii) adopting low carbon energy technologies. In addition to the environmental imperative, the economic case for these activities gains higher priority as the prices of electricity, gas, and liquid fuels increase. Low-carbon, energy-saving technology options that are available to mining industry companies lead to projects with return rates that must compete alongside other capital-intensive projects considered by mining company boards. Energy projects frequently involve longer payback periods and lower rates of return than those of competing bids for capital, such as new mineral property developments. For energy services companies that specialize in the financing, construction, efficient operation, and maintenance of energy projects, the same returns and payback periods can be considered acceptable or even attractive.

Jan 1, 2012

By Gerald M. Bandholz

Exxon Minerals Company, a division of Exxon Corporation, has been exploring for base metal deposits in the Precambrian volcanic rocks in northern Wisconsin since 1970. Aerial electromagnetic surveys of the area, conducted in 1974, reported an anomaly, near Crandon, in Forest County. In the summer of 1975, the first diamond drill entered the anomaly, representing the 25th prospect Exxon had drilled in Wisconsin. This first hole revealed significant mineralization containing zinc and copper. Subsequent drilling confirmed the discovery of a sizeable zinc-copper massive sulfide are body. 1.1.2 Location The deposit is located in northeastern Wisconsin within a topographical high called the Northern Highlands region. The deposit lies about 5 miles directly south of Crandon and about 2 miles east of State Highway 55 on Sand Lake Road (see fig. 1). Other local communities include Rhinelander 28 miles west, Antigo 45 miles south, and Iron River and Iron Mountain, in Michigan, 75 and 44 miles east and north of Crandon respectively. In relation to the lakes and streams, the deposit lies 0.25 miles north of Little Sand Lake, and about 1 mile south of Swamp Creek.

Jan 1, 1981

By T. Klemetti

Moisture deterioration of clay-rich roof rocks causes high numbers of roof falls in coal mines in humid summer months. Rocks with high moisture content are generally weaker and can further deteriorate when subjected to wetting and drying cycles. As a result, it is important to evaluate the moisture-sensitivity of roof rock prior to mining. The National Institute for Occupational Safety and Health (NIOSH) has evaluated three moisture-sensitivity index tests on roof rocks from 23 U.S. coal mines. The three tests were the University of Kentucky Weatherability test (Weatherability test), the Consol Energy Water Sensitivity test (Water Sensitivity test), and the NIOSH Immersion test (Immersion test). Of these three tests, the Weatherability and Water Sensitivity tests are more reliable in classifying the moisture-sensitivity of roof rocks. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By Cissé Kane, Klaus Hieronymi, Mathias Schluep, Gerry Newson, Susanne Dittke

"E-waste is currently the fastest growing waste stream in South Africa as well as in many other African countries. Informal collectors, dismantlers and recyclers based in Africa play an increasingly larger role in the processing of e-waste under generally unacceptable social and environmental conditions. In direct response to this trend, and as part of Hewlett Packard’s international Extended Producer Responsibility, the project “e-Waste Management in Africa” was started in 2007 in cooperation with the Global Digital Solidarity Fund (DSF) and the Swiss Federal Laboratories for Materials Testing and Research (Empa). This project is investigating the e-Waste situation in various African Countries, including South Africa, while actively supporting the development of practical, socially just and environmentally acceptable local e-waste management solutions. To this end, the project has been funding the development of a pilot project in Cape Town, South Africa since February 2008, supporting the start-up of a low tech/highly labour intensive material dismantling and recovery facility (MRF) for the pre-processing of e-waste. The aim is to test the feasibility of an integrated value adding local e-Waste management system, designed to maximize the potential of refurbishment, repair, re-use, dismantling and recycling of equipment, with environmentally responsible disposal as a last resort only. The project also seeks to incorporate the current informal e-waste processing activities, by transforming them into sustainable and environmentally sound operations. The MRF acts as a nucleus, raising awareness, and providing training and education to previously disadvantaged individuals as a means of creating opportunities for entrepreneurship in the technical maintenance, dismantling and waste-to-art project sectors."

Jan 1, 2008

By Kambhampati C. Rao, Cecil Lue-Hing, Nabih P. Kelada, William B. Willborn

improvements in the analytical techniques for cyanide speciation can furnish useful information about the behavior of the different cyanide species in the receiving environment. This could be of help to the environmentally concerned public and the regulatory agencies in the assessment of cyanide limits for effluents, stream quality, and land disposal of cyanide bearing wastes. In addition the ability to distinguish the free cyanide and the weakly bound cyanide from the strong ULTRAVIOLET IRRADIATION UNIT (LAMP, COIU3' HOUSING) FIGURE 1 complexes, as well as transformation to thiocyanate is also needed by different industries, such as mining and metal finishing, etc., to evaluate the efficiency of several processes. Cyanide has been used for the recovery of gold since the late 19th century. Although cyanide leach solutions are mostly recovered and used again, a large quantity of cyanide bearing wastewater becomes unfit for use and has to be treated before it can be released into natural waterways.

Jan 1, 1992

By Richard Engelmann

The mining industry, in particular the coal industry, has experienced the implementation of some major environmental regulatory programs during the past two decades. Over the coming decade the coal industry will probably experience only "fine tuning" of the regulatory programs they now operate under. The rest of the indus- try, however, appears to be on the verge of coming under a major new regulatory effort by the Environmental Protection Agency. Litigation and resulting court decisions will be the main force driving further changes in the SHCRA (Surface Mine Control and Reclamation Act) regulatory program. These changes are anticipated to be minor in compar- ison to earlier changes. EPA, however, is preparing a regulatory program which may carry as much impact to the rest of the mining industry as SNRA was to coal. Details of this program have yet to be worked out. Changes in the way EPAts Clean Air Program is applied to mining could also significantly impact the mining industry.

Jan 1, 1989

By R O. Laidlaw, J L. Mauk

The Coeur d'Alene mining district in northern Idaho, USA is the second largest producer of silver in the world. Mesothermal silver-lead-zinc veins occur in the metasedimentary rocks of the Belt Supergroup with five main types of associated hydrothermal alteration: 1) feldspar destruction, 2) hydrothermal bleaching, 3) carbonatisation, 4) sulfidation, and 5) silicification. Hydrothermal bleaching is characterised by hematite destruction with associated siderite and quartz veins and veinlets, coarse euhedral pyrite and magnetite. Bleached zones envelop both mineralised and barren veins and extend for metres to tens of metres into the wall rocks. Carbonatisation consists of addition of siderite, which occurs as veins, veinlets, stockwork, irregular blebs or spots, and coarsely disseminated grains, depending on the relative distance from the main vein structure. Siderite envelops nearly all mineralised veins, relates to all other alteration types and extends from several metres to tens of metres into the wall rocks. Pyrite and galena alteration dominate sulfidation and are associated with some mineralised veins. Pyrite alteration strongly correlates with siderite alteration and exists in three main forms: a) very fine-grained pyrite flooding, which can extend for metres to tens of metres into wall rocks; b) coarse-grained, euhedral pyrite, which is sporadic and associated with the redox boundary in hydrothermally bleached zones; and c) small isolated zones (6 - 15 cm) of medium-grained, subhedral to euhedral pyrite associated with pervasive siderite alteration. Where present, disseminated galena extends for metres to tens of metres into the wall rocks. Silicification is characterised by veins, veinlets, stringers, irregular patches and variable hardness in siltites and commonly appears in association with hydrothermal bleaching and siderite alteration. Although related to mineralisation, silicification is sporadic and in most places a clear envelope around mineralised veins cannot be identified.

Jan 1, 2001

By Robert Maquil, Gilles Didier, Walter Steiner

"The 1580 m long dual-tube motorway tunnel Markusberg near Schengen, Luxembourg experiences strong swelling phenomena in each tube related to a 35 m wide diagonally crossing rock layer, some150 to 200m from the east portals. Overburden over the roadway is 26 to 30 meters. Tunnel construction started in 1998 and the tunnel was opened in 2003. The tunnel was driven downgrade from the West, the heave phenomenon started to occur as the tunnel approached completion. No indications of the presence of anhydrite and dissolved sulphates were known prior to tunnelling. Water samples had been taken from the beginning of construction and the concentration of anions and cat ions determined. Sulfate content was substantial, in one well it reached 22 mg/l, this high concentration requires the presence of other ions, in particular sodium and chlorine. Based on the knowledge at the time of construction heaving ground was removed from the tunnel invert and a free space was left below the roadway that is covered by a transversely spanned slab. In addition a series of posttensioned tiebacks were installed below the sidewalls. The void left in 2003 was 1.7m high and closed to less than 0.5 meters in 2007 then it became necessary to widen the free space. A central trench was dug with a height of about 2.5 meters and the benches were lowered.Level surveying had been carried out since 2002. In 2006 two extensometers were installed, one in the zone of strongest heave, the second at the edge of the swelling zone. The extensometer in the center of the swelling zone indicated heave with an essential constant rate with seasonal variations, the heave is concentrated in layer from 2 to 5 meters that heaved by nearly 300 millimeters within 5 years or 60 mm/year, which equals to approx. 1% extension per year. At the abutments heave rates of 20 mm/year where the support resistance is higher were observed. With data from other case histories a relation of heave rate with support resistance was established. Based on the numerous field observations hypotheses for the complex in-situ swelling processes, involving rock mechanics, mineralogical, soil mechanics and hydrogeological aspects were developed"

Jan 1, 2015

By A. Juganda, Jr. Bogin, S. A. Lolon, J. F. Brune, J. W. Grubb

"A longwall gob is mainly filled with broken rocks from the collapsed roof and becomes a porous medium where explosive methane-air mixtures can accumulate. In bleeder ventilation systems, this mixture can migrate out of the gob into the longwall face and other active areas in the mine during barometric or ventilation-induced pressure changes. When external pressures change, the gob does not perceive this disturbance instantly but with a delay due to air flow resistance in the porous gob material. The delay of gob response to outside pressure changes increases the pressure differential across the gob and may cause an outflow of explosive air mixtures from the gob into the adjacent bleeder entries. With computational fluid dynamics (CFD) modeling, researchers at the Colorado School of Mines have evaluated the impact of gob pressure fluctuations on the outgassing of the explosive gas zones (EGZs), the magnitudes and rates of pressure changes, the volumes as well as the potentials location of outgassing if it occurs. INTRODUCTION The air pressure field in underground mines is controlled by many factors such as operating fan settings, ventilation controls, surface atmospheric conditions, and other local events that can intermittently disturb mine pressure, including blasting, roof falls, or inundations. Mine fan settings are rarely changed. Mine atmospheric pressure fluctuations due to adjustments in ventilation controls occur more often during the mining process. Atmospheric conditions and barometric pressures can generate fluctuations in mine pressure on a large scale. Atmospheric pressures change regularly every day but can fluctuate abruptly and become increasingly hazardous in adverse weather conditions. Investigations conducted in coal mines in the United States, Australia, Poland, and South Africa observed higher methane emissions from the gob during periods of falling atmospheric pressures, which led to mine explosions (McIntosh, 1957; Boyer, 1964; Kissell et al., 1973; Fauconnier, 1992; Belle, 2014; Wasilewski, 2014; Lolon et al., 2015). Falling external pressures are understood to cause potential outflow of explosive mixtures from the gob, while rising pressures may push fresh air into the gob. This phenomenon is widely known as gob breathing. The actual processes that trigger gob breathing are not fully understood, nor are the parameters that contribute to the process. Other major events such as roof falls or fan failures can also change the pressure conditions in the mine. In contrast to atmospheric pressure changes, these events can change mine pressures much more rapidly or immediately. TIME LAG AND GOB BREATHING CONCEPT In a bleeder ventilation system, the pressure in the gob is designed to be lower than that of the headgate entries and the longwall face. Air from the gob and gate entries flows towards the tailgate-bleeder returns. When the external pressures are disturbed, this designed pressure arrangement may change, potentially resulting in increased outflow from or inflow into the gob."

Jan 1, 2017

By Wyborn L. A I, Idnurm M, Hinman M. C

Comparison of the Proterozoic Apparent Polar Wander Path (APWP) for Australia with the corresponding geology of northern Australia suggests that a number of discrete interplate tectonic events, manifested on the APWP as bends or inflections, may have controlled sedimentary basin evolution, ore fluid production and the timing of mineralisation. Similar features in the Phanerozoic APWP for the North American plate appear to correlate with major orogenic events, basin deformation, movement and 'entrapment' of hydrocarbons and minerals. Interplate tectonic events cause intraplate deformation which in turn controls the subsidence/uplift and sedimentation histories of the basins. Interplate events are thus responsible for creating, deforming and destroying sedimentary basins and the associated petroleum and mineral systems. The basins of northern Australia show remarkable similarities in the successions of volcanic and sedimentary deposits. Unconforrnities of regional or sometimes only local extent have been mapped between the major sedimentary sequences and it is predicted that interplate tectonic events corresponding to bends or inflections on the APWP directly reflect the processes that have produced these widespread unconformities. These processes are also likely to have controlled the geometry and character of the fluid migration pathways and hence the mineralising events. Palaeomagnetic studies of Proterozoic rocks in sedimentary basins provide a tool for predicting the timing of regional mineralisation events, particularly for low-temperature mineral systems. The techniques, when coupled with systematic regional basin analysis, using petroleum exploration techniques, may identify a number of new mineral 'plays' in northern Australia. Prominent inflections in the APWP occur at approximately 1700, 1670, 1650, 1600, 1540, and 1480 Ma. Each of these may be related to a regional compressional deformation, important mineralising event, or significant change in style and type of sedimentation. Most appear to be associated with magnetic overprints. Some of the inflections between 1400 and 540 Ma may also mark significant events in the evolution of Meso- and Neoproterozoic basins. Further work is required to correlate inflections in the APWP with alteration events in order to understand their regional significance.

Jan 1, 1994